Two incompatible worlds
Two types of hydraulic brake fluid exist for bicycles, and they are completely incompatible:
| Type | Brands | Chemical base |
|---|---|---|
| Mineral oil | Shimano, Magura, Tektro | Paraffin oil |
| DOT (4 or 5.1) | SRAM, Hope, Hayes, Formula | Polyethylene glycol |
Why you NEVER mix them
Seals are made from materials specific to each fluid type:
- DOT in a Shimano brake: seals swell and disintegrate within 24-48 hours
- Mineral oil in a SRAM brake: same catastrophic failure




